Switch construction



April 15, 1958 H. F. MASON 2,831,082

' SWITCH CONSTRUCTION Filed Dec. 11, 1952 4 Sheets-Sheet l INVENTOIP.

HOWFMD F. lvmso/v BY H/S fiTTOR/VEYS.

HERE/S; K/ECH, F05 r51? a'Hnmels EMU-M}.

H. F. MASON SWITCH CONSTRUCTION April 15, 1958 4 Sheets-Sheet 2 FiledDec. 11, 1952 573 Z/a 5 26 22a ll'l/Ifll'llllllll lNl/ENTOR. Howe/e0 F.A/mso/v BY HIS HTTORNEYS. Hake/s K/EcH, Foam/e & HQRR/S \BY QLQ.

United States Patent SWITCH CONSTRUCTION Howard F. Mason, Los Angeles,Calif., assignor to Mason Electric Corporation, a corporation ofCalifornia Application December 11, 1952, Serial No. 325,401 12 Claims.(Cl. 200--68) This invention relates to snap action switches and oneobject of the invention is to provide a combination of elementsoperating with fast make and break that may be embodied in diverse typesof switches including lever switches, rotary switches, push-typeswitches and various types of relays. It will be apparent that theinvention is widely applicable to various specific uses. For the purposeof disclosure and to illustrate the principles involved, the inventionwill be described herein as embodied in two specific switches foraircraft use, one switch being of the lever type and the otherswitchbeing of the rotary type. These specific disclosures will provideadequate guidance for those skilled in the art who may have occasion toapply the same principles to the construction of other switches forother specific uses.

It is an important object of the invention to provide a snap actionswitch that operates in a positive manner in the sense that thecircuit-controlling switch member of the switch snaps from onepredetermined position to another for opening or closing a circuitwithout any possibility of pausing or stopping between the twopredetermined positions. The desired snap action occurs regardless ofhow the switch is manually manipulated by the operator. In general, thisobject is attained by the combination of a carrier for the switch memberand an actuating means to move the carrier with lost motion between theactuating means and the carrier, these elements being acted upon bycooperating yielding means. In a preferred form of the invention, afirst yielding means provides a detent action tending to hold the switchmember at predetermined positions along its path of movement, and asecond yielding means provides the snap action to shift the switchmember without pause from one predetermined position or station toanother.

The path along which the switch member moves is provided with recessesat each of the predetermined stations for the switch member and thefirst yielding means continuously presses the switch member laterallytoward this path to cause the switch member to releasably engage'therecesses. Each of these detent recesses provides a pair of oppositelysloping cam surfaces at each station for cooperation with the switchmember. Thus the path along which the switch member moves is dividedinto zones for Cam action of the switch'member at the predeterminedstations and zones of free movement of the switch member between thepredetermined stations. The first yielding means, which may be termed adetent yielding means, is effective in the cam zones to tend to centerthe switch member at each station and the second yielding means iseffective in the zones of free movementbetween the stations to providethe required snap action from station to station. In the preferredembodiments'of the invention the switch member is in the form of arotary member rotatably carried by the carrier to roll along thedescribed path from station to station. The use of such a rotary switchmember not only improves the cam action at ICC each station but alsoreduces friction to facilitate the snap action from station to station.

To carry out the purposes of the invention the range of lost motionbetween the actuating means and the contact carrier operated thereby isat least equal to the length of a zone of free movement between stationsto permit the second yielding means to function over the length of azone of free movement independently of the actuating means. Preferably,the second yielding means which produces the snap action is soconstructed that it tends to maintain the carrier at a central positionwith respect to this range of'lost motion. Thus with the switch memberengaging a recess at a given station and the actuating means free tomove, the second yielding means will tend to hold the actuating means ata position centralized with respect to the given position. On the otherhand, if the actuating means is manually shifted progressively out ofthis centralized position the second yielding means will tend to causethe carrier to follow the movement of the actuating means. The detentyielding means, however, is strong enough to prevent the carrier frominitially following the actuating means.

By virtue of this arrangement and the described relationships there arefour stages of the operation of the switch to shift the switch memberfrom a given station to the next station. These four stages occur insequence as the actuating means is manually moved progressively from aposition centralized at the given station toward a position centralizedat the next station. In the first stage of switch operation the rotaryswitch member lingers in the contact recess to store energy in thesecond yielding means. in the second stage the actuating means forcesthe switch member to the brink of the recess. In the third stage thesecond actuating means snaps the rotary switch member to the brink ofthe recess at the next station. The last stage is the seating of therotary switch member in the recess by cam action.

It is another object of the invention to meet certain problems involvedin the construction of a heavy duty switch of this type, for example, aswitch for frequent operation to control fifty or more amperes ofcurrent at 30 or more volts. Some of these problems are primarilyelectrical since they arise from arcing in the making and breaking ofcircuits. Other of the problems are more or less mechanical.

The snap action for fast make and fast break is, of course, part of thesolution for modifying the undesirable effects of arcing at thecontacts.If it is further contemplated that relatively large contact bodies willbe employed which, by virtue of their massiveness, tend toremainrelatively cool and therefore tend to quench arcs. A specialfeature of the invention in this regard, however, is the employment of aswitch arrangement that divides the arcing effect between two arcs inseries. At each circuit closing position of the switch member, theswitch member shorts or bridges a pair of contacts thus dividing thearcing effect between the two contacts.

Some arcing is, of course, inevitable and a further object of theinvention is to keep the effect of arcs on the material of the contactsfrom reducing the efliciency of the switch. This object is accomplishedlargely by extending the contacts into the zones of free movement of theswitch member so that arcing occurs at points spaced away from therecesses in which the switch member is normally seated. This object isalso attained in part by the use of a rotary switch member which tendsto polish the contact surfaces and thus restore the effectiveness of anysurfaces that may be damaged by arcing.

A further object of the invention is to provide for accurate positioningof the switch member at the pair of contacts at each station withadequate pressure against a each of the two contacts. A feature of theinvention is that this object is attained by giving the switch memberseveral degrees of freedom so that it may accommodate itself to thepairs of contacts regardless of structural inaccuracies and so that theswitch member may equalize its pressure between the two contacts in eachpair.

The various objects, features, and special uses of the invention may beunderstood from the detailed description to follow considered with theaccompanying drawings.

in the drawings, which are to be regarded as merely illustrative:

Figs. 1 to 4 are simplified diagrammatic views showingfour successivepositions of a switch mechanism constructed in accord with-theinvention;

Fig. 5. is a longitudinal sectional view of a. two-pole, double-throwswitchof the lever type embodying the invention, the section being takenasindicatedby the line of Fig. 6;

Fig. 6. is .a sectional viewtaken along the. line 66 of Fig.

Fig. 7 is an enlarged fragmentary detailed view of the structure shownin Fig. 5, the fragmentary view being partly in section and partly inelevation;

Fig. 8 is a greatly enlarged fragment of Fig. 6;

Fig. 9 is asection taken along the broken line 99 of Fig, 6 to disclosethe pairs of contacts of the switch in plan view;

Fig. 10 is a longitudinal sectional view of a rotary gang switchembodying the invention;

Fig. 11 is a transverse sectiontaken as indicated by the line lit-ll ofFig. 10;

Fig. 12 is an enlarged fragmentary section taken as indicated by theline 12-12 of Fig. 10;

Fig. 13 is a transverse section taken as indicated by the line 13.13 ofFig. 10;

Fig. 14 is a view similar to Fig. 13 showing the parts in a secondposition;

Fig. 15 is an enlarged detail of Fig. 10;

Fig. 16 is an enlarged fragmentary section taken as indicated by theline 1616 of Fig. 15;

Fig. 17 is an enlarged fragmentary view of a pair of contacts of theswitch as seen in plan; and

Fig. 18 is aview similar. to Fig. 14 illustrating a modi' fication ofthe; structure.

In the diagrammatic Figures 1 to 4 illustratingthe principles underlyingthe invention; a series of switch contacts 20, 21, 22 togetherwithtintervening portions of a-body of non-conducting material 23provides a path for acircuit-controlling switch member 25. The switchmember 25 is preferably in the form of a metal roller. A recess 26 is,provided at. each of the three stations represented by the.threecontacts 20, 21 and 22,to form seats for releasable engagement bythe switch member 25. In this instancesince the'switch member 25 is inthe form of a roller, preferably each of the recesses 26 has the samecurvature as the periphery of the roller. In the construction shown, therecesses 26 are formed in the contacts and each contact is wider inthedirection of the path than the recess.

The rotary switch-.member 25, is journalled in a suitable carrier 30which, in this instance, is in the form of a block of rubber or othersimilar elastic material. A suitable actuating means generallydesignated 31 to shift the carrier 3% and the switch member 25 fromstation to station is operatively connected with the carrier in asuitable manner to provide a range of lost motion between theactuatingmeans and the carrier. In the construction shown, the actuating means,311 is inthe. form of a lever and one arm of the lever is in the form ofan actuating handle 33. To provide thev desired lost motion between theactuating means andthev carrier the. second arm of the lever may be inthe form. of a yoke 35 having two arms 36 straddling the carrier.

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It is contemplated that suitable yielding means will be provided topress the rotary switch member 25 laterally towards the path along thecontacts thereby to cause the rotary switch member to releasably engagethe recesses 25 at the various stations. Such yielding means mayincorporated in the carrier 30 or in the actuating means 31 or may actbetween the actuating means and the carrier or between the carrier andthe rotary switch memher. in the present example of the invention thedesired yie' use is incorporated in the constructionof the actuatingmeans 3].

The actuating means 31 is made in two sections that are slidinglytelescoped' together and are continuously urged apart by a coil spring37. One of the two sections comprises the handle 33 and a ballenlargement 4i) integral therewith by means of which the actuating meansis pivotally mounted in a suitable bearing assembly 41. The othersection of the actuating means comprises the yolre 35' which'has'a shank42 slidingly extending into the handle section against the coil'spring37.

Inaddition to the'coilspring 37 the switch mechanism has a secondyieldingmeans effective between the actuating means 31 and the carrier3ii=to tend to position the carrier centrally inits range'of'movementrelative to the actuating means. In the combination shown in Figs. 1 to4 this second yielding means isin the form of a leaf spring 43mounted-on-the yoke ES-to' provide two leaf spring arms 45 between thetwo yoke arms 36. These two leaf spring arms 45-tendto hold the carrier38 and the yokeI-id'ccntralized with-respect to each other with the axisof the rotary switch-member in line with the axis of the actuatingmeans.

As may be seen in Fig. l the-carrier 30 moves through its range ofrelative movementwith arocki'ng action which is resisted by the leafspring arms 45 and is limited in a positive manner by the yoke arms 36.It is also to he noted that when the carrier 30 is rocked out'ofitsnormal central. position it is placed under diagonal compressionbetween the base of the yoke 35' and'the rotary switch member 25. Thecompression of the elastic carrier body cooperates with the coil spring37 'innrgingthe rotary switch member into engagement with the recesses26.

The path for the rotary switch member- 25 providcdby the contacts 20, 21and 22 together with thedntervcning non-conducting material isconcentricito'tne nivot axis of the lever actuating means 31'. Sincethe'rotary switch member 25 is yieldingly pressed toward thisarcuatc'path, each of the recesses 26 in eifectconstitutesa pair of oppositely inclined cam shoulders for the rotaryswitch member. Thus thearcuate path is divided into cam zones represented by,the recesses 26and intervening. zones where the rotary switch member 25 may movefreely, the intervening zones of free movement being arcuate racewaysfor the rotary switch. member. Since the contacts 259, 21 and 22 arewider than the corresponding. recesses 26 formed therein each of thearcuate'raceways for free movement of the rotary switch member includesportions of the contacts.

The mode of operation of the switch mechanism shown in Figs. 1 to 4 maybe readily understood when it is considered that when the actuatingmeans is shifted out of its normal central position relative to thecarrier andswitch member, the yielding tendency of the switch member 25to remain seated in a recess 26 is sufficient to resist the'yieldingtendency of the leaf spring #33 to dis lodge the switch member, and whenit is further coir sidered that the range of movement of the carrier 3-9relative to the yoke 35 and .the ability of the leaf spring the fourstages which: will'now be described in more" detail.

In the normal position of the switch mechanism with the switch member 25in a recess 26 at one of the contact stations, say at the contact 21,and with the'handle 33 of the lever actuating means free from manualrestraint, the first yielding means 37 in the handle 33 exerts pressureto hold the switch member 25 seated in the recess of the contact 21. Thetwo leaf spring arms 45 yieldingly engaging opposite sides of thecarrier 30 hold the handle 33 centralized with respect to the contact 21with the axis of the handle in line with the axis of the rotary switchmember 25. When the handle 33 is manually rocked progressivelycounterclockwise, as viewed in the drawings, toward a positioncentralized with respect to the next contact 22, initially the rotaryswitch member 25 remains snugly seated in the recess of the contact 21.As a result the carrier 30 rocks relative to the moving actuating means31 with consequent storing of energy by stressing of the left leafspring arm 45:. This first stage terminates at the end of the range ofrelative movement between the carrier and the actuating lever when theleft arm 36 of the yoke 35 abuts the left leaf spring arm 45.

The second stage of the operation of the switch consists in the positiveor direct action of the actuating means on the carrier 30 as the leftyoke arm 36 forces the carrier to move and cause the rotary switchmember 25 to climb up the slope of the recess of the contact 21. In Fig.1 illustrating this second stage, the handle 33 has been swung 8 fromits starting position. As the rotary switch member 25 climbs up theright cam shoulder provided by the recess it causes energy to be storednot only by compression of the spring 37 in the handle 33 but also bydiagonal compression of the elastic body of the carrier 30. When the arm33 has been moved 11 from its starting position, as shown in Fig. 2, therotary switch member 25 nearly reaches the right brink of the recess inthe contact 21. Only slight additional movement will place the rotaryswitch member at the edge of the arcuate raceway or zone of freemovement.

The third stage of the operation then takes place automatically andindependently of the actuating means 31, this third stage consisting inthe snap action of the carrier 30 across the zone of free movement intothe cam zone at the next contact 22. In this snap action the left leafspring arm 45 releases its stored energy to the carrier 33 and there isa certain further release of stored energy as the carrier swings outof-its diagonally compressed position. The momentum of the carrier andthe rotary switch member is sutficient to throw the carrier past thecenter of its range of relative movement in opposition to the right leafspring arm 45 as well'as in opposition to the compression of the carrieras it assumes a second diagonalposition. In all instances of compressionof the carrier 30 whether diagonally or centrally there is, of course,also accompanying compression of the spring 37 in the handle 33.

The fact that the throw of the carrier 30 is sutficient to stress theright leafspring arm 45 does not result in return movement of thecarrier, however, because the throw is sufficient to cause the rotaryswitch member 25 to cross the left brink of the recess in the nextcontact 22 where cam action again becomes effective. In comparing Figs.2 and 3 it will be noted that the handle 33 has been advancedcounterclockwise from an 11 position to a 12 position and the carrierhas been snapped across the arcuate raceway into the cam zone at thenext contact 22.

If at this time the handle 33 were released, the cam action provided bythe pressure of the rotary switch member 25 against the left cam surfaceof the contact 22 would be sufiicient for carrying out the fourth stageof the switch operation which consists of the switch mem ber 25 rollingdown the cam shoulder to seat firmly in-75 the bottom of the recess atthe contact 22. The released actuating means would follow this cammingmovement of the rotary switch member 25 and the leaf spring 43 actingbetween the actuating means and the carrier would centralize theposition of the actuating means relative to the contact 22. In thenormal operation of the switch, however, the handle is not released atthe position shown in Fig. 3, the normal follow-through by the operatorshand continuing through the final cam operation at the contact 22.

Certain important features of the invention may be appreciated byfurther analysis of the switch operation. In the first place there is aunique cycle of storing and releasing energy. The first stage of thedescribed switch operation stores energy in the left spring arm 45, thesecond stage in which the switch member climbs up the cam surface at thecontact 21 results in further storage of energy in the coil spring 3'7as well as in the elastic material of the carrier 30, the third stageresults in the release of a major quantity of energy from the let leafspring arm 45 and the storage of a lesser quantity in the right leafspring arm 45, and the fourth stage results in final release of theenergy stored in the coil spring 37, in the right leaf spring arm 45,and in the resilient body of the carrier 30.

A second feature is the manner in which the currentcarrying eificiencyof the switch is maintained by increase of pressure between the switchmember 25 and the contact 21 as the switch member rolls from its normalseated position to the brink of the contact recess. In its normal seatedposition the switch member has a maximum area of mutual contact with thecontact 21. This mutual area is reduced as the switch member isdislodged from its seat, but the resulting cam action increases thepressure between the switch member and the contact, the increase beingalong a steep pressure gradient because of the diagonal compression ofthe carrier in combination with the compression of the coil spring 37.Thus the increase in pressure between the switch member and the contactas the switch member climbs a recess slope compensates for reduction ofthe area involved, and such pressure compensation maintains thecurrent-carrying ability of the cooperating parts.

A third feature is that each of the contacts is wider than thecorresponding recess 26 in the contact so that arcing in making andbreaking circuits occurs at edge portions of the contact spaced awayfrom the recess. Thus the arcing is remote from the normal contact seatof the switch member. It is to be further noted that any effect ofarcing on an edge portion of a contact is offset by the tendency of therolling switch member to restore damaged surfaces of the contacts,especially since the rolling action occurs under substantial pressure.

A further feature of the invention with regard to arcing is the factthat the edge portion of each contact lies in a zone of free movement ofthe switch member. in the snap action of the carrier the rotary switchmember attains substantial velocity before it leaves one contact memberand, of course, the switch member approaches the edge portion of thenext contact member at even higher velocity. Such rapid make and breakminimize the arcing eifect and, as heretofore stated, each ofthecontacts 20, 21 and 22 will tend to stay cool and therefore tend toquench any arcs that occur.

Figs. 5 to 9 show how the basic switch mechanism of Figs. 1 to 4 may beembodied in a lever-type switch to serve the purpose of a conventionaltoggie switch. The parts of the switch previously described 1 to 4 areindicated by corresponding numerals. In this instance the mechanism isadapted to serve the purpose of a single-pole, double-throw switch.

The switch construction shown in Figs. 5 to 9 inciudes a box-likehousing 50, preferably of plastic nonconducting material, which isclosed on its lower side by a thick arcuate wallSl concentric to thepivot axis of the acuat a! ing means The thick wall 51 is unitary witha-pair of parallel side walls 52 which, as shown in Fig. 5, telescopeinto the housing 50 and are suitablybonded thereto.

The previously mentioned contacts 20, 21 and'22 are embedded in thearcuate wall 51 but in this instance there is a second row of threecontacts a, 21a and 224 (Fig. 9) to provide a pair of contacts at eachstation to be bridged by the rotary switch member 25. The contacts 20and 22 in the first row are connected, respectively, with externalterminals 53 and 54 and the external terminals are provided with theusual terminal screws 55. The intermediate contact 21 in the first rowis a dummy or dead-end terminal. The three terminals 20a, 21a and 22a ofthe second row are all integral parts of a single conductor 56 which isunited with a third terminal 57 having a terminal screw 55.

The arcuate wall 51 and the two side walls 52 form an arcuate channel ofnon-conducting material to confine the yoke and the carrier 36 forguidance of the rotary switch member 25. non-conducting arcuate rib 60that extends. between the two rows of contacts, the rib being of thesame height as the six contacts out being formed with recesses 61 ateach of the three switch stations, these recesses being deeper than thecorresponding contact recesses 26. By virtue of this arrangement therotary switch member 25 rides and seats on the pair of contacts at eachstation, but rides on the central arcuate rib 66 between stations. Thearcuate raceway for free movement of the switch member between stationsis formed in part by the arcuate rib 60 and in part by edge portions ofthe contacts adjacent the contact recesses 26.

Preferably the switch is of fluid-tight construction with the arcuatewall 51 bonded to the housing 50in a fluidtight manner and with theactuating means 31 also sealed off in the region of the pivotal mountingof the ball enlargement 40. In the construction shown a tubular member62 mounted on the switch housing 50 has the usual external threads 65 toreceive the usual retaining nut (not shown) for permanently mounting theswitch. The tubular member 62 is in threaded engagement with the wall ofthe housing 50 and is provided with a radial flange 66 on its inner endfor cooperation with an inner sealing gasket 67 of suitable material.This particular switch has what may be termed a momentary return spring70 to cooperate with the yoke 35, as will be explained later, whichspring is a leaf spring having a base portion 71 apertured forengagement between the flange 66 and the sealing gasket 67.

The tubular member 62 may be adapted in any suitable manner to serve asa fluid-tight bearing for the ball enlargement 40. For example, thetubular member 62 may be formed with an internal tapered shoulder 72 andmay be threaded to receive a bushing 73 having a similar taperedshoulder 74, the two tapered shoulders serving to confine a pair ofbearing rings 75. The two bearing rings 75 have spherically curvedsurfaces to embrace the ball enlargement 40 and are made of suitablematerial to permit universal movement of the ball enlargement and at thesame time to form an eifective seal around the ball member. A feature ofthe invention is the use of rings for this purpose made of a plastichaving the trade name Teflon which offers exceptionally low resistancetoarotary movement of the ball enlargement 40.

The elastic body of rubber-like material that comprises the carrier 30is yieldingly embraced by the leaf spring arms 45 which tend to maintainthe carrier and actuating means centralized relative to each other.Preferably the elastic body is cut away centrally to form a p'air, ofup.- wardly extending corner portions 78 for contact'with the baseportion of the yoke 35, which corner portions are stressed incompression diagonally when the carrier rocks relative to the yoke asheretofore described.

In the construction shown inthe drawings, the carrier body 30 ishollowed out to receive'the rotary switch mem- This channel is formedwith a central 8 ber.25 and: to"form,lparal1el side walls. 79 to supportthe opposite ends of an axle pin 80 for the rotary switch member. Asbest shown in Figs. 5 and 7 the rotary switch member 25: is preferablyin the form ofa metal ably the axle pin 80 is sufficiently flexible toadd to this freedom of the rotary switch member and for this purpose theaxle pin may be made of piano wire.

It is apparent that the rotary switch member 25 has several'degrees offreedom for movement. It is movable along'the arcuate path of contactsconcentric to the pivot axis of the lever or actuating means 31; it ismovable radially of that axis by virtue of'the telescoped constructionof the leveractuatingmeans; it is rotatable about the axisof thelever,i. e., about anaxis radially of the pivot axis of the lever; and ithasfreedom to rock about an axis perpendicular to the radial axis, i. e.,about the normal axis of the axle pin 80. it will be apparent that theelasticity of the carriage 30 contributes to all of these variousdegrees of freedom.

The momentary return spring 7 0, which may be omitted, has an effectiverange of elastic movement sufficient to cause the rotary switch member25 to be shifted from the station at the contacts 22-22a to the stationat the intermediate pair of contacts 21-21a. Thus, if the lever 33 ismanually shifted to carry the switch member to the pair of contacts22-22a from the contacts 21-21a, the switch will stay in the newposition only so long as manual force is applied to the handle 33 andwhen the handle is released the switch will'return automatically to themiddle position shown in Fig. 6. In this middle position no circuits areclosed by the rotary switch member 25 but in the left position asviewed, in Fig. 6, the switch terminal 57 is connected to the switchterminal 53 and'in the right position the switch terminal 57 isconnected to the switch terminal 54.

Figs. 10 to 17 illustrate how the principles of the invention may beincorporated'in a rotary switch having eight positions and sixteenswitch contacts. Preferably the rotary switch is of a construction thatfacilitates the uniting of any desired number of switch units to form agang switch operated by a single actuating shaft. Fig. 10, by way ofexample, shows two such switch units united to provide a rotary gangswitch having eight positions with two separate rotary switch memberselectrically interconnecting corresponding-pairs of switch terminals ateach of the eight positions.

Each of the two switch units shown in Fig. l0 comprises the basiccombination of a stator in the form of a thick-walled cylinder. of asuitable plastic nonconducting material, an actuatingmeans 91in the formof a rotor also made of nonfconducting plastic material, and a carrier,generally designated 92, which carries a rotary switch member 95. Eachof the two stator cylinders 90 has embedded therein eight pairs ofcontacts 96 which extend'to the exterior of the switch and are providedwith external'terminal screws 97.

The housing for the two-unit gang switch comprises the two cylindricalstators, 90, an end plate 98, a second end plate 99 and an intermediatetransverse plate 106',

\ this assembly being united by a series of longitudinal tie rods 101andnuts 102.

The end plate 98 is formed with an externally. threaded boss or tubularextension 105 in which is;journalled an actuating shaft 106 that isoperatively connected to the rotor 91 of the left-hand switch unit asviewed in Fig. 10. In the construction. shown the actuating shaft 106 isunitary with a thin disc 107 at its inner end, which dischas afiangedrim portion 108 embedded in the material of the left-hand-rotor;Thus one end of the rotor is 9 supported by the actuating shaft 106, theother end being journalled in the intermediate transverse plate. 100.

The left-hand rotor 91 is formed with a circular series of lugs orlongitudinal projections 110 which mate with corresponding recesses inthe right-hand rotor 91 to operatively interconnect the two rotors andto rotatably sup port one end of the second rotor. The other end of thesecond rotor is journalled in the second end plate 99. Each of therotors 91 is suitably hollowed out diametrically to house a carrier 92and to permit the required freedom for the carrier to move relative tothe rotor through a range of sufiicient extent for the snap actionheretofore described.

As best shown in Fig. 15, the principal parts of the carrier 92 are: aU-shaped frame 114 pivotally mounted in the rotor 91 for rotationcoaxially of the rotor; a diametrical tubular member 115 mounted on theU-shaped frame; a pair of opposed torsion springs 116 which tend to holdthe U-shaped frame in a central position with respect to its range ofmovement relative to the rotor; a yoke 117 which journals the rotaryswitch member 95 and has a shank 118 extending into the tubular member115; and a coil spring 120 in the tubular member 115 which surrounds theshank 118 and urges the yoke 117 radially outward.

A tubular member 115 extends through the base portion of the U-shapedframe 114, being welded thereto, and is additionally supported by twoaxial pins 124. Each of the axial pins 124 is mounted in one of the legsof the U-shaped frame 114 and has an enlarged head 125 welded to theoutside of the frame to serve as a trunnion for pivotally mounting theframe in the rotor 91. -As indicated in Fig. 10, the rotor 91 is formedwith a pair of radial slots 127 the inner ends of which serve asbearings for the trunnions with the trunnions positioned on the sameaxis as the rotor.

Each of the two torsion springs 116 is wrapped around an axial pin 124with one leg of the torsion spring resting on the base of the U-shapedframe 114 and with the other leg normally resting on an angular support130 carried by the U-shaped frame and also normally resting on acorresponding shoulder 131 at the end of a corresponding slot 132 in therotor 91. Normally the two torsion springs 116 are in balancedopposition to maintain the carrier 92 in a normal position centralizedwith respect to the rotor 91. This normal position is shown in fulllines in Figs. l0, ll, 13 and 15.

Preferably the rotary switch member 95 is mounted on an axle pin 135 inthe manner heretofore described to give the rotary member a certainfreedom to rock relative to the normal axis of the axle pin. The axlepin 135 is mounted in the two legs of the yoke 117 with end portions ofthe axle pin extending beyond the yoke. The extended end portions of theaxle pin 135 are guided by radial grooves 136 formed in the legs of theU-shaped frame 114.

It is apparent that the rotary switch member 95 has the various degreesof freedom heretofore described and that the coil spring 120 continuallyurges the rotary switch member outward against the surrounding stator90. The stator 90 in combination with the two circular rows of contacts96 provides a continuous circular path for the switch member 95 and theindividual contacts 96 are formed with recesses 137 that serve the samefunction as the recesses in the contacts of the first form of theinvention.

Preferably the brinks of the recesses 137 are slightly chamfered orrounded off as shown at 138 in Fig. 12. It has been found that formingthe contact recesses with the rounded shoulders 138 eliminates a certaintroublesome tendency for the metal of the contacts to be upset by impactof the switch member against the walls of the contact recesses. Byvirtue of the rounded shoulders 138 the switch member 95 moves into arecess 137 in smooth manner without damaging impact and the polish ingaction of the switch member on the metal of the contact eliminates anyminor damage to the contact that may i tend to occur at the twoshoulders 138.

The operation of the rotary switch may be readily understood since it isfundamentally the same switch operation as heretofore described. When arotor 91 is rotated progressively by the actuating shaft 196 away fromthe normal centralized position of the rotor with respect to the carrier92 at a given switch station, the pressure exerted by the coil spring120 is sufficient to maintain the switch member initially in the recess137 at the switch station. Consequently initial rotation of the rotor 91out of its normal position causes one of the torsion springs 116 to bestressed. Fig. 14 shows in full lines how continued progressive rotationof the rotor 91 eventually brings inclined wall surfaces 140 of therotor against the two legs of the U-shaped frame 114 whereupon the rotoracts in a positive manner to dislodge the switch member 95 from therecess 137.

With continued rotation of the rotor 91 the switch member 95 is carriedto the brink of the recess 137 whereupon the stressed torsion spring 116snaps the carriage 92 toward the next switch station where the switchmember enters the next cam region as heretofore described.

The cam action powered by the coil spring tends to center the switchmember and carrier at the new station and the two torsion springs 116cooperate to tend to centralize the position of the rotor 91 relative tothe new station.

The modified rotary switch shown in Fig. 18 is largely identical to thestructure heretofore described as indicated by the use of correspondingnumerals to indicate corresponding parts. The modification consists inchanging the internal configuration of the rotor 91a so that the rotarymovement of the carrier 92 relative to the rotor is limited by abutmentof a wall surface 141' against the end of the tubular member 115.

In all forms of the invention the actuating means that cooperates withthe carrier has what may be termed a kicker portion for impact againstthe carrier at the end of the range of relative movement of the carrier.The purpose is to kick the switch member out of engagement with therecess at the station so that the snap action can occur to carry theswitch member towards the next switch station. It is desirable, ofcourse, that the arcuate path for free movement of the rotary switchmember 95 be provided by smooth and accurately concentric surfaces. Tothis end it is contemplated that the two rows of contacts 96 will beembedded in the stator 90 when the stator is molded or cast and thatsubsequently the stator together with the embedded contacts will bemachined and processed to achieve the desired accurate concentricity.

The specific embodiments described in detail for the purpose ofillustration will suggest to those skilled in the art various changes,substitutions and other departures from my disclosure that properly liewithin the spirit and scope of the appended claims.

I claim as my invention:

1. In a switch, the combination of: an arcuate, concave contact pathhaving a center of curvature and having circumferentially spaced,radially inwardly directed, recesses therein and having thereon at leastone stationary contact in which one of said recesses is formed; a freelyrotatable roller contact engaging and movable along said contact pathand receivable in each of said recesses; a contact carrier for saidroller contact located radially inwardly of and movable adjacent andparallel to said contact path; an axle carrying said roller contact andmounted on said contact carrier and providing free rotation of saidroller contact relative to said contact carrier; actuating means movableabout said center of curvature of said contact path for moving saidcontact carrier adjacent and parallel to said contact path; meansproviding a lostmotion connection between said actuating means and saidcontact carrier; kicking means carried by said actuating means andengageable with said contact carrier for limiting the range of lostmotionbetween. said actuating. means and said contact carrier soas tokick said roller contact out of each of said recesses; and resilientmeans for biasing said roller contact into engagement with said contactpath.

2. A switch as defined in claim 1 including another resilient meansconnecting said actuating means and said contact carrier for centeringsaid contact carrier insaid range of lost motion between said actuatingmeans and said contact carrier.

3. A switch as-defined in claim 1 wherein said. resilient meanscomprises means for progressively increasing the force biasing saidroller contact into engagement with said contact path in response tomovement of said roller contact toward-the center of said contact path.

4. A switch as defined in claim 1 wherein said means providing saidlost-motion connection comprises a reel:- able connection between saidactuating means and said contact carrier, whereby said contact carriermay, rock relative to said actuating means Within said range of lostmotion provided by said limiting means.

5. A switch as set forth in claim 4 wherein said con tact carrier isengageable with said actuating means at either or" two circumferentiallyspaced points between said contact path and the center of said contactpath to provide said rockable connection between said contact carrierand said actuating means.

6. A switch as defined in claim 1 wherein said recesses havesubstantially the same cuivature in crosssection as said roller contact.

7. A switch as defined in claim 1 wherein said contact path defines partof a cylinder.

S. Aswitch according to claim 1 wherein said contact path defines a fullcylinder.

9. A switch as set forth in claim 1whereinsaid stationary contact iscircumferentially wider than said recess therein.

1%. A switch according to claim 1 wherein said range of lost motion isat least equal to the distance between said recesses.

11. A switch according to claim 1 wherein said axle is flexible and.resilient and wherein said roller contact engages said axle throughout acentral portion thereof only with clearance on either end of saidcentral portion to permit said roller contact to rock relative to saidaxle.

12. A switch including a roller contact and a flexible and resilientaxle carrying said roller contachsaid roller contact engaging said axlethroughout a central portion thereof only with clearance on either endof said central portion to permit said roller contact to rock relativeto said axle.

References Cited in the file'of this patent UNITED STATES PATENTS1,921,765 Meuer Aug. 8, 1933 2,163,919 Siegel June 27, 1939 2,505,548Hutt Apr. 25, 1950 2,565,863 Linn Aug. 28, 1951 2,625,619 Rigert Jan.13, 1953 2,707,741 Collura May 3, 1955 2,708,227 Collura May 3, 1955FOREIGN PATENTS 23,423 Great Britain Nov. 3, 1908 of 1908 571,395 GreatBritain Aug. 22, 1945

